人肠神经元PAR-1介导的信号传导通路在IBD发生发展中的作用

Our recent study revealed that Protease/proteinase-activated receptors (PARs) play a major role in the pathogenesis of inflammatory bowel disease (IBD). Further studies has shown for the first time that PAR-1 activation is most relevant for activation of human submucous neurons, while PAR-2 is prevalent in rodent enteric neurons. PAR-1-AP evoked a prominent spike discharge and intracellular Ca2+ concentration transients in human submucous neurons. However, the PAR-1 mediated signal transduction pathway in the pathogenesis of IBD and the physiological importance still remain unknown. The IL-21 of human intestinal tissue elevated in patients with IBD stimulates MMP-1 synthesis. So we hypothesize that the IL-21 may affect PAR-1 expression by the activation of PAR-1-IP3K signaling pathways in the enteric neurons. PAR-1-mediated in intracellular Ca2+concentration change, and causing enteric nervous regulating function obstacle, and produce the symptoms of patients with IBD. We use molecular biology, immunohistology and electrophysiology methods, such as neuron imaging using voltage- and calcium-sensitive dyes，voltage clamp ussing chamber and whole cell patch clamp recording, to verify a PAR-1 mediated IL-21-PAR-1-Ca2+ signal transduction pathway in human enteric neurons which contribute to the pathophysiology of IBD. This project will provide a new target for the treatment of in IBD patients.

摘要：我们的研究结果证实蛋白酶激活受体(PARs)在IBS/IBD的发病机制中具有关键性的作用，进一步研究发现人肠粘膜下神经丛神经元上的PAR-1是一个起主导作用的受体而并非动物实验所表明的PAR-2的作用，PAR-1被激活可导致细胞内钙浓度升高。但PAR-1介导的信号传导通路及其在IBD发生发展中的作用不清楚。IBD病人肠组织中升高的IL-21刺激MMP-1合成增加。由此我们推断IL-21可通过激活PAR-1-IP3K信号途径影响PAR-1在肠神经元的表达，尽而影响了PAR-1介导的细胞内Ca2+浓度，导致肠神经调节功能障碍，产生IBD病人的症状。本课题拟采用分子生物学、电生理学等方法，直接利用外科手术中肠切除组织和IBD病人的肠活检组织标本研究人肠神经元PAR-1介导的IL-21-PAR-1-Ca2+信号传导通路及其在IBD发生发展中的作用，为临床该类疾病的治疗提供新的靶点。

免疫功能障碍被认为在炎症性肠病（inflammatory bowel disease, IBD)包括溃疡性结肠炎(ulcerative colitis, UC)和克隆恩病 (Crohn's disease, CD)的发病机制中起重要作用。研究发现考尼伐坦（Conivaptan）治疗可以缓解实验性肠炎的发展，Conivaptan是抗利尿激素/血管加压素(Vasopressin，VP）V1a和V2受体的非选择性拮抗剂，然而，conivaptan在减缓IBD的肠炎症状中的免疫作用机制尚不清楚。我们研究发现CD4+T细胞表达V1a受体。V1a受体激活可显著促进CD4+T细胞向T helper 1 (Th1)细胞分化，conivaptan治疗可阻断这一过程，显著减轻DNBS诱导的结肠炎，V1a受体激活并没有引起CD4+T细胞内钙离子浓度（[Ca2+]i）增加。本课题利用在体动物及离体实验技术，研究结果证实conivaptan通过调节CD4 + T细胞稳态对结肠炎发挥保护作用，为临床IBD的治疗提供了新的靶点。